1. Field
The field of the invention relates to medical devices, and more particularly, to medical devices and methods of their use for treating tumors or other targeted bodily tissue using electrical energy.
2. Background
Tissue may be destroyed, ablated, or otherwise treated using thermal energy during various therapeutic procedures. Many forms of thermal energy may be imparted to tissue, such as radio frequency electrical energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction.
In particular, radio frequency ablation (RFA) may be used to treat patients with tissue anomalies, such as liver anomalies and many primary cancers, such as cancers of the stomach, bowel, pancreas, kidney and lung. RFA treatment involves the destroying undesirable cells by generating heat through agitation caused by the application of alternating electrical current (radio frequency energy) through the tissue.
Various RF ablation devices have been suggested for this purpose. For example, U.S. Pat. No. 5,855,576 describes an ablation apparatus that includes a plurality of wire electrodes. Each of the wires includes a proximal end that is coupled to a generator; and a distal end that may project from a distal end of a cannula. The wires are arranged in an array with the distal ends located generally radially and uniformly spaced apart from the catheter distal end. The wires may be energized in a monopolar or bipolar configuration to heat and necrose tissue within a precisely defined volumetric region of target tissue. The current may flow between closely spaced wire electrodes (bipolar mode) or between one or more wire electrodes and a larger, common electrode (monopolar mode) located remotely from the tissue to be heated. To assure that the target tissue is adequately treated and/or to limit damaging adjacent healthy tissues, the array of wires may be arranged uniformly, e.g., substantially evenly and symmetrically spaced-apart so that heat is generated uniformly within the desired target tissue volume. Such devices may be used either in open surgical settings, in laparoscopic procedures, and/or in percutaneous interventions.
Currently, tumor near a vessel may be difficult to ablate. This is because the vessel continuously provide blood to the tumor during an ablation procedure, thereby carrying heat away from a targeted region. As a result, it may be difficult to achieve a complete burn for the tumor near the vessel.